[IronPython] Rewrite of WSGI handler

[Christopher Baus]

I'm beginning to wonder if we really need the reload IronPython
functionality in WSGI.  It adds some complexity for not a lot of real
gain.  I thought one reason for reloading the interpreter would be to
reload all the modules, but that can be done via WSGI middlewear.

Also I ran into a problem with the flup session middlewear.  It uses the
third, exec_info, parameter of start_response, which isn't supported in
our current implementation.   I will admit I am not totally sure how to
properly implement this.  According to the pep it has something to do with
not sending the headers of the response twice.

http://baus.net/